Effect of gonadotropins on oocyte maturation in vitro: an animal model

Abstract

Objective: Analysis of the effects of human-derived gonadotropin drugs, FSH and LH (Repronex) and hCG (Novarel), on oocyte maturation, using a porcine oocyte in vitro maturation system as a culture model.

Design: Randomized research experimental study.

Setting: Academic basic research laboratory.

Animals: Prepubertal gilts that were slaughtered in the local slaughter house.

Intervention(s): Oocytes will be exposed to immunofluorescent staining and confocal laser scanning microscopy: Western blot analysis on cumulus-oocyte-complexes following treatment with different concentrations of the gonadotropin drugs Repronex, Novarel, and a Repronex and Novarel combination.

Main outcome measure(s): Analysis of porcine oocyte spindle and chromosomal configuration with alpha-tubulin-fluorescein isothiocyanate antibody and propidium iodide staining. Porcine oocyte mitochondrial distribution and aggregation pattern staining was assessed with Mito Tracker Red CMXRox probe. Porcine oocyte cortical granule distribution was observed via peanut agglutinin-fluorescein isothiocyannate staining; Western blot analysis detected extra-cellular signal-regulated kinase 1/2 activation in cumulus cells.

Result(s): An increase of gonadotropin concentration in the culture medium resulted in an increase in the following: the percentage of oocytes reaching metaphase II, normal configuration of the spindle, normal chromosomal alignment, cortical granule migration, and mitochondrial aggregation. Levels of nuclear and cytoplasmic maturation peaked as the concentration of gonadotropins approached its threshold level.

Conclusion(s): Addition of a threshold concentration of the gonadotropin drugs Repronex, Novarel, and a combination of the two can significantly improve porcine oocyte maturation in vitro.